The answer varies according to the environment:
Technically, it take takes 4-6 hours if it's done in one session and all the pre-requisites and requirements are already in place.
However, that is rarely the case and a lot of the time unexpected delays can occur (ports not open, pre-requisites not installed, can't get an a SA account, etc.).
Therefore, a more accurate estimation would be 2-3 session each of 2-4 hours.
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Note that very large environments with multiple pools, Front Ends, Edge server or a requirement for HA can prolong the installation time.
Below is a summery summary of hours for basic installation:
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